Condensation of phenol with methyl pyruvate

Methyl pyruvate reacts with phenol, in the presence of hydrogen chloride, yielding 3-(4-hydroxyphenyl)-3-methyl-2-coumaranone (1a), methyl 2,2-bis-(4-hydroxyphenyl)-propionate (2a) and methyl 2-(4-hydroxyphenyl)-2-(2-hydroxyphenyl)(3a). The structure of 1a was determined by the X-ray diffraction method and that of 2a was based on the spectral data. The latter compound was not isolated, its structure (3a) was assigned basing on the GCMS analyses and analogy with the compounds 1a and 2a. The crystal and molecular structure of racemic 3-(4-acetoxyphenyl)-3-methyl-2-coumaranone (1b) was determined at room temperature. The triclinic unit cell contains a couple of enantiomeric molecules connected by weak C-H . . . .O hydrogen bonds.